Interesting

This is interesting. The animation is decent. The song got on my nerves a little after some time. I think you could do more with it. Maybe extend the loop so that it includes more. I liked how you used "Mehico" instead of "Mexico" relying on the Spanish term which seemed to fit well with the song. I would like to see the mouse do more than just stand there with the cheese.

WHERE IS THE GAMEPLAY?

There is no gameplay in here whatsoever.
The music is funny though, and the animation was average.

If this was a longer flash movie, then it would of been funny.